Computer users encrypt files by setting passwords when document files and text files are generated, saved, and distributed. Thus, only authorized user accesses a file. Also, due to encryption functions supported by application software itself for various file formats, a user is readily able to encrypt files.
In order to read an encrypted file, a password that has been set in encryption needs to be entered. If a user could not remember the password, a file reading would not be permitted. Also, a file which a user has encrypted may become an evidence or a clue capable of clearing criminal relation. In this case, the file encryption may make discovery of evidences difficult in a forensic process.
Accordingly, password search software or dedicated hardware such as password decryption FGPA may be used in order to find the correct password. Also, data parallel-processing characteristics of GPU may be used to find the password.
When the password search software is needed, a user is able to use the free or low-priced software. However, since tools performing sequential CPU operations are used, the time taken to find the password is usually long. If the dedicated hardware such as FPGA or ASIC for password decryption is used, high-speed password searching is possible. However, since the expensive dedicated equipment manufactured only for password searching can not be used for other purposes, the dedicated hardware is not cost effective and not suitable for general use.